| Because the modern economy relied heavily on fossil energy consumption that resulted increasingly imminent of fossil energy and great pressure to environment. Development ofeconomy required to reduce using of fossil energy,lightweight vehicle is a important part instrategies of energy conservation and emission reduction of China, new lightweight application materials including aluminum alloy, magnesium alloy, titanium alloy, highperformance plastics, porous foam and composite materials etc. Friction stir welding hasadvantage of wide application range, and also can realized dissimilar materials which physical property exist huge difference.Therefore,this paper used friction stir welding technology toweld ABS plastics,ABS and aluminium alloy. The results of process experiments showed thatthe friction stir welding can realize the welding of ABS, ABS and 6082 aluminum alloy.In order to verify the welding applicability of friction stir welding to non- metallicplastics, friction stir welding technology was used to weld ABS plastics.It can realizedeffective connection of friction stir butt welding of ABS in process parameters of rotation speed of 1300r/min, pressure depth of 0.15 mm, welding speed of 20mm/min. The jointstrength can reached 20.5MPa and ran up to 68% of ABS base,surface morphology of forwardside and retreating side reaching agreement and no obvious burrs and no fusion of albinism. It can also realized good connection of friction stir spot lap welding of ABS plastic. Thesequence of main factors affecting the mechanical properties of the joint was: residence time>rotation speed >welding speed. Molecular chains realized effective fusion and cross linking in the middle of plates,cross section presented in relatively smooth.Joints appeared delaminationphenomenon, the fracture started from the mixing layer and bonding interface between upperand lower plate.There was a big difference in the joint of friction stir spot welding of ABS plastics andaluminum alloy between whether the stirring head had a stirring pin or not. The joint achievedreliable connection between 6082 and ABS,the surface of joint was relatively flat and beautiful. But the optimal welding parameters was not the same in different welding processand tensile shear load gap is comparative larger. That is because highest temperature of jointwhich was welded by stirring head with no pin was higher 100℃than stirring head with pin,so the former joint connecting area and shear strength is larger than the latter. The fractureposition of the joints were all concentrating in ABS side.The joint appeared two fracturemodes in optimal welding parameters: brittle stripping fracture and plastic fracture of base material, the latter mode which included two forms: along the joints trend to fracture, along astraight line of the edge of joints extend fracture. Joint has undergone three fracture stages:crack initiation, stable growth, rapid expansion. It formed a clear and distinguishing crack growth pattern in tensile shear failure, the crack propagation velocity is the fastest in the thirdstage in the section.Fracture of joint originated from the bubble defects and micro cracks inthe interface between aluminum alloy and ABS. The main bonding force of spot joint weremolecular and mechanical force in the contact interface: intermolecular bonding force,ABS molecular and Al2O3 oxide of aluminum alloy surface formed crosslinking under frictionalheat; mechanical bonding force,the end of resin molecular chain, aluminum alloy aluminumatoms and surface oxide nailed to another base material. |
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